VIPER Foam GunVIPER Foam Gun RT300S The Viper Foam Gun is the easiest and most cost effective way to clean radiators, plate heat exchangers, mechanical equipment and hardware, coils and other HVACR equipment. The foam injection method covers the surface of the coil much faster and increases contact time over conventional pressure sprayers. Theres no heavy equipment to carry and no need to pre dilute, just plug the Viper Foam Gun into any garden hose connection,